Food processing, preparation, serving and consumption produces large quantities of reusable soiled dishes, table ware, pots and pans, and other equipment often referred to as utensils. Before such items can be reused, they must be washed and usually dried. Industrial and institutional cleaning of such goods is generally done in machine washing equipment of various types. Essentially all washing machines employ an aqueous detergent solution to clean the soiled dishes and other food handling equipment. The aqueous detergent solution is generally sprayed onto the soiled items in an enclosed chamber so that both the solubilizing action of the solution and the mechanical action of the spray against the items combine to clean the soiled dishes and the like.
Restaurants and institutions already have available several types of detergent products for use in dishwashing machines, including granular compositions, liquids, and solid bricks or blocks. Some of these are directly introduced into the machine; these in-machine dispensers are particularly useful with relatively small machines. In other cases, particularly for large commercial machines, the detergent is dispensed automatically by various types of feeding equipment. However, the latter dispensers are expensive, especially in regard to production and maintenance.
More recently, block-formed detergents for domestic and institutional dishwashing machines have been developed, which have the advantage of being dimensionally stable. These detergents are dissolved by simply spraying with water, and then are delivered to the wash machine in solution. Since institutional detergents often have a high caustic alkali content, contact with the skin should be avoided. Block-formed detergents are much safer to handle and thus also superior in this regard.
One type of automatic equipment for producing a detergent washing solution from a solid cast detergent block is disclosed in Fernholz et al, U.S. Pat. No. 4,569,781. U.S. Pat. Nos. 4,569,780 and 4,569,781 describe a detergent container suitable for use in automatic detergent dispensers adapted for dispensing detergents in block form. A molten detergent is poured into the container and allowed to solidify. The detergent is subsequently dissolved from the container on contact with a stream of fresh service water. The advantage of a block-form detergent and dispenser combination of this type is that, with proper handling, contact with the skin is virtually eliminated. However, this type of dispenser is external to the dishwashing machine and requires plumbing connectors and in some configurations, electrical connections in order to be operational.
A dispenser which is internal to the dishwashing machine is disclosed in U.S. Pat. No. 4,808,236, issued to Davis. The Davis dispenser has a cup-like container which holds a detergent block suitable for dispensing in a dishwashing machine. The container has a removable lid with a tab which covers an opening in the container's top. The Davis dispenser is placed on the dishwasher's scrap tray with a firm tap to cause the detergent block to drop down and rest on the scrap tray. When the lid and tab are removed, the machine's washing water enters the opening in the container top and flows downwardly along the side of the detergent block, thereby forming a detergent solution. The detergent solution flows out of the container's open mouth bottom.
The Davis container, however, has several drawbacks. First, the detergent block is used up quite quickly, so that the user must frequently remove the container from the dishwashing machine and substitute a new detergent block. In addition, the concentration of the detergent solution for most of the block's life is excessively high, after which the concentration drops precipitously until the concentration is too low for effective cleaning. In other words, the detergent is dispensed at a non-uniform and uneconomical rate.
The invention addresses these and many other problems associated with currently available products for the in-machine dispensing of dishwashing detergent.